Re: [PATCH v6 5/6] acpi/ghes, cxl/pci: Process CXL CPER Protocol Errors

[Koralahalli Channabasappa, Smita]

On 2/3/2025 11:03 AM, Luck, Tony wrote:
> On Thu, Jan 23, 2025 at 08:44:20AM +0000, Smita Koralahalli wrote:
> > When PCIe AER is in FW-First, OS should process CXL Protocol errors from
> > CPER records. Introduce support for handling and logging CXL Protocol
> > errors.
> >
> > The defined trace events cxl_aer_uncorrectable_error and
> > cxl_aer_correctable_error trace native CXL AER endpoint errors. Reuse them
> > to trace FW-First Protocol errors.
> >
> > Since the CXL code is required to be called from process context and
> > GHES is in interrupt context, use workqueues for processing.
> >
> > Similar to CXL CPER event handling, use kfifo to handle errors as it
> > simplifies queue processing by providing lock free fifo operations.
> >
> > Add the ability for the CXL sub-system to register a workqueue to
> > process CXL CPER protocol errors.
> >
> > Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx>
> > Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> > ---
> >   drivers/acpi/apei/ghes.c | 49 ++++++++++++++++++++++++++++++++++++++++
> >   drivers/cxl/core/pci.c   | 36 +++++++++++++++++++++++++++++
> >   drivers/cxl/cxlpci.h     |  5 ++++
> >   drivers/cxl/pci.c        | 46 ++++++++++++++++++++++++++++++++++++-
> >   include/cxl/event.h      | 15 ++++++++++++
> >   5 files changed, 150 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> > index 4d725d988c43..289e365f84b2 100644
> > --- a/drivers/acpi/apei/ghes.c
> > +++ b/drivers/acpi/apei/ghes.c
> > @@ -674,6 +674,15 @@ static void ghes_defer_non_standard_event(struct acpi_hest_generic_data *gdata,
> >   	schedule_work(&entry->work);
> >   }
> >   
> > +/* Room for 8 entries */
>
> Any science behind the choice of "8" here? This comment is merely
> stating what the #define is used for, not why 8 was chosen.

The choice of "8" was arbitrary and not based on a specific rationale. 
If there are better heuristics or considerations for determining the 
optimal number of entries, I’d appreciate any suggestions.

Thanks
Smita